Towards sustainable fisheries in Lake Tanganyika: integration of genetics, environmental data and stakeholder involvement.

The objective of the proposal is to improve applied biological knowledge of two key fish species of Lake Tanganyika (LT), which provide more than 60% of the annual fish production (200,000 ton): the clupeids Stolothrissa tanganicae and Limnothrissa miodon commonly known as LT sardines (locally known as kapenta). LT provides livelihood and food security to millions of people. This lake, the second-oldest and second-deepest in the world, is also a textbook case for evolutionary biology. We aim to increase knowledge of clupeid biology with an integrated, innovative and cost-effective strategy to monitor lake-wide and long-term trends in clupeid stocks with regard to the impact of climate change and overexploitation. Improved knowledge will allow to formulate specific management strategies for a sustainable pelagic fishery on LT sardines.

We hypothesize that sardines consist of geographical subpopulations (stocks) that are adapted to lake-wide environmental gradients, and that regional declines in captures are due to environmental changes or increased fishing pressure over time.

To formulate the much needed management strategies, three objectives are presented:

Objective 1:How many clupeid stocks does LT harbour? Each stock requires adaptive management strategies in order to ensure stock resilience. We aim to determine clupeid stock structure as well as the temporal stability of these stocks, including fish migration and abundance, the degree of population mixing, and potential adaptation to lake-wide environmental gradients.

Objective 2:How did recent historical environmental change affect clupeid species? A better understanding of the consequences of environmental change over past decades is essential to understand future scenarios for the development of sustainable fisheries. To answer this question, we will analyse historical clupeid samples to investigate if and how past lake-wide environmental change affected genetic structure and dynamics of clupeid populations over the course of a few decades (1930-2016).

Objective 3:Can we reveal crucial information on the causes for decline of fish stocks and support possible management strategies by using stakeholder knowledge and field data to construct a Bayesian Belief Network? Integration of local knowledge, current policies and stakeholder perception is valuable to increase the acceptance level of proposed management strategies. We aim to build a comprehensive knowledge base on LT clupeids including the present state of fisheries policies and fishermen's practices to improve the integration of research results and stakeholder concerns to propose an adapted management plan for a sustainable fishery in this model system in which fisheries of international importance are mainly carried out on a local scale.